Ubuntu kernel configuration

[Derek Broughton]

Michael J. Lynch wrote:

> Anyway...what we've found is that the "/boot/config-$(uname -r)"
> files can NOT be used to recreate the "/boot/vmlinux-$(uname -r)" and
> "/boot/initrd.img-$(uname -r)" files.
...
> In /usr/src/linux-$(uname -r) run "make oldconfig"
> Do remainder of build process

That's a pretty big chunk of work to call "remainder".  Despite your
colleagues 20 years of Linux experience, I suspect he isn't familiar with
make-kpkg, which is how the Debian/Ubuntu kernels are built.

> We always end up with vmlinuz and initrd images that a significantly
> different that the originals.  The *big* problem is that initrd ends
> up being huge and wont fit in memory (256M).  The original initrd that
> was supposedly generated using the config is tiny in comparison.  If
> we look at the config, practically *everything* is being compiled as
> modules.  This explains why initrd is so large.  

It really doesn't.  Now, I would expect the vmlinuz image to be the same
size in any case, but the initrd doesn't need to hold _all_ the kernel
modules, only the ones needed to boot.  mkinitrd has its own configuration
file.
-- 
derek